Greywater, such as residential waste-water discharged from showers, sinks, dishwashers and washing machines, typically has been combined with blackwater, or raw sewage, which must be stored in septic systems or treated at municipal sewage treatment facilities. However, the additional volume contributed by combining greywater with blackwater can significantly increase the treatment cost of blackwater.
An alternative method of treating greywater, which avoids combination with blackwater, is treatment with aerobic bacteria by distributing greywater to a soil bed. However, disposal of greywater in soil beds has been difficult because erosion of soil near the point of discharge often causes collection of greywater in large pools. Generally, collected greywater will putrify and smell if it is left stagnant, such as typically occurs during formation of pools in eroded soil beds.
One attempt to distribute greywater to a soil bed without significant erosion of soil and consequent pooling of greywater includes directing greywater into a perforate tube having apertures distributed along a substantial portion of the length of the tube. However, the pressure of flowing greywater diminishes along the length of such a perforate tube, thereby causing a disproportionate amount of the greywater to be discharged through apertures proximate to an inlet end of the perforate tube. The greywater conducted through the apertures near the inlet end, therefore, are conducted through those apertures at a higher volumetric flow rate and at a higher velocity than through apertures which are distal to the inlet end. A higher volumetric flow rate and higher velocity of flow through apertures near the inlet end of the perforate tube typically causes erosion of soil from around the tube near the inlet end. Therefore, greywater often tends to pool in the eroded soil bed near the inlet end of the perforate tube and consequently putrifies by anaerobic decomposition of the greywater. Also, the apertures of the perforate tube can become clogged with particulates and by organisms within the soil bed, such as insects and worms, thereby causing uneven and diminished distribution of greywater from the perforate tube to the soil bed.
A need exists, therefore, for a new system and method for distributing greywater within a soil bed which overcome or eliminate the aforementioned problems.